1. Field of the Invention
The present invention relates to wheel-based warehouse style pallet jacks, and particularly to a portable material handling equipment or pallet jack stop formed by a wheel cradle with a small ramped approach on one side, and slots or ridges on the bottom. The device secures the main pivoting wheel of the pallet jack, thus preventing it from rolling around uncontrollably, endangering personnel and property.
2. Description of the Related Art
When storing or transporting goods in bulk quantities, it often becomes necessary to place such goods on pallets in order protect them from damage and facilitate their movement. These pallets are usually made of wood and elevate the bulk materials several inches above the warehouse floor, freight train car, or truck bed. These pallets, in turn, can be lifted and moved by warehouse personnel or other material handlers using devices known as pallet jacks. These pallet jacks resemble hand operated forklifts, in that they possess two or more heavy metal horizontal tines with metal rollers on their bottom side. These tines are usually connected at one end by a heavy metal bracket that houses a hydraulic pump connected to a vertical metal stanchion with hand controls on its upper end, and a supporting pivot wheel at its bottom.
The operator of the pallet jack moves materials by inserting the tines of the pallet jack in the open spaces created by the pallets beneath the materials. The operator then xe2x80x9cjacksxe2x80x9d the pallets with their materials above the supporting surface and then, primarily using the supporting pivot wheel, moves the palletized materials to their new location. The sturdy metal structure and powerful hydraulic pump of the pallet jack will allow one person to quickly move hundreds of pounds of materials, thus greatly reducing the need for extra warehouse personnel and freight terminal loading and unloading crews. These metal structures and pump mechanisms may cause the pallet jack to weigh several hundred pounds, even when unloaded. Whether unloaded or loaded, the heavy metal pallet jacks tend to move along their bottom rollers and pivot wheels if the surface where the jack was placed becomes unstable, as in the back of a freight car or cargo carrying vehicle. The same results may occur if the jack is stored in an area with a sloping surface. If adequate precautions are not taken to restrain the movement of an unused pallet jack, its uncontrolled movements may cause extensive property damage. These uncontrolled movements of the pallet jacks could also seriously injure warehouse workers and other personnel. One way to restrict the movement of an unused pallet jack is to elevate and restrict the movement of its pivot wheel. Elevating the pivot wheel, immobilizes the rollers on the bottom the of the pallet jack""s tines. Restricting the movement of the pivot wheel at the structural base of the jack generally immobilizes the entire device, even when the supporting surface is unstable or sloping.
The problem of restricting the movement of heavy items with roller, wheeled feet or bases is not limited to the problem of pallet jacks. Larger pieces of home furnishings, (i.e. pianos, beds, sofas, etc.) automobiles and motorcycles present very similar problems to warehouse persons and freight carriers. Solutions have been devised to similarly restrict the movement of these wheeled devices utilizing pieces of equipment with long, heavy, sloping ramps having wheel cradles of various depths and at various elevations. The problem with devices having long heavy ramps is that often their size and weight can create additional material handling difficulties. Wheel cradles of various depths will often adequately restrain the wheel(s) of a heavy item to prevent rolling, but may not adequately address the problem of resistance to the sliding movement of a fixed wheeled support.
A number of devices have been proposed for restraining the movement of pallet jacks or similar heavy wheeled items.
U.S. Pat. No. 5,839,863, issued Nov. 24, 1998 to L. Johansson, describes a parking device for immobilizing a hand truck on the floor of a truck or cargo-hauling vehicle during vehicle movement. The device includes a two-part frame, the first of which is longer and thicker than the other part and is ramped on one side in order to facilitate the rolling of a hand truck into the parking device. The second part of this device is a rectangular cradle or cavity for restraining the wheels of the hand truck. The bottom of the device is either coated with a material having a high coefficient of friction, or has feet coated with a similar material to prevent slipping relative to the floor of the cargo-carrying vehicle. U.S. Pat. No. 3,391,760, issued Aug. 8, 1966 to H. A. Gonser, discloses a similar device in which a sturdy sheet steel wheel lock block is used to restrain the movement of the wheel of an automobile. This sheet steel device is formed generally into the shape of a rectangle with beveled sides that allow the wheel of the automobile to be rolled up and then down into the interior restraining space.
U.S. Des. Pat. No. 389,796, issued Jan. 27, 1998 to D. G. Olson, shows a long shallow ramped platform and elevated rectangular wheel restraint for a pallet jack""s pivot wheel. A roped handle is also shown as part of this invention. U.S. Des. Pat. No. 444,441 shows a wheel chock configured as a disk with a sloped or ramped perimeter that rises to a certain height and then slopes downward to an interior space that would serve to restrain the wheel of a vehicle or other wheeled device. U.S. Patent Application Publication No. US 2001/0050034, published Dec. 13, 2001, shows an elevated rectangular metal skid assembly for restraining the movement of wheeled vehicles during transportation. U.S. Pat. No. 1,480,758, issued on Jan. 15, 1924 to W. T. Hight, describes a caster cup for restraining the movement of heavy furnitures items by slightly elevating and restraining their wheeled feet in a circular or polygonal block of wood, thick glass or porcelain.
Other patents showing devices for restraining the movement of heavy wheeled devices or furnishings by restricting the movement of their supporting wheels include U.S. Pat. No. 2,687,538, issued Aug. 31, 1954 to P. A. Marzillier (elevated wheeled bed leg interlock with fixed base); U.S. Pat. No. 2,699,628, issued Jan. 18, 1955 to B. Auer (a furniture caster cup made of moldable material for receiving the legs of heavy furnishings); U.S. Pat. No. 2,870,872, issued Jan. 27, 1959 to G. G. Rapp (a non-skid moldable automobile wheel chock block with metal side frames); U.S. Pat. No. 4,911,270, issued Mar. 27, 1990 to T. S. Hudson (a rigid chock for preventing the rolling movement of a vehicle wheel); U.S. Pat. No. 5,046,587, issued Sep. 10, 1991 to D. C. Jones (a trailer tongue wheel chock and support); U.S. Pat. No. 5,210,903, issued May 18, 1993 to J. L. Horning (furniture caster stop and process of immobilizing a caster); U.S. Pat. No. 5,332,066, issued Jul. 26, 1994 to G. R. Pickeral (boat trailer rest for restraining the trailer wheel); and U.S. Pat. No. 6,386,331, issued May 14, 2002 to R. L. Scheffer (method and apparatus for securing a shopping cart).
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed. Thus a pallet jack stop solving the aforementioned problems is desired.
The pallet jack stop is a compact, portable, sturdy cradle for restricting the movement of the pivot wheel(s) of a warehouse style pallet jack, thus restricting the movement of the pallet jack itself when not in use. The cradle is generally rectangular in shape, having a closed bottom with a short sloping ramp or bevel on one side and a rectangular carrying handle on the opposite side. The bottom side has a ridge around its outer edges and deep grooves underneath the ramped side. The cradle is made of a molded or extruded dense rubber, or other suitable sturdy resilient material.
The pallet jack is sturdy, easily portable and compact. It can easily be carried and used with one hand by adults who are physically fit enough to engage in warehouse and freight handling work. When not needed, the pallet jack stop can be quickly stored out of the way of warehouse traffic, safely placed on top of palletized materials or placed on a hook or holder provided on the pallet jack. The pallet jack stop is made of material of sufficient strength and elasticity as to allow it to repeatedly bear the weight of standard unloaded and loaded pallet jacks under the entire range of environmental conditions found in warehouses and cargo carriers, to include standard allowances for impact loading with safety factors. The pallet jack stop is made of materials that comply with the normally accepted criteria for combustibility, smoke generation and environmental protection.
Accordingly, it is a principal object of the invention to provide a pallet jack stop for immobilizing the pivot wheel of a pallet jack, so that a loaded or unloaded pallet jack will not move when the device is used on a sloped or moving surface.
It is another object of the invention to provide a portable pallet jack stop that is compact and light enough to be deployed by one adult who is physically fit for warehouse or freight handling work using one hand.
It is a further object of the invention to provide a pallet jack stop that does not need to be set up and can be easily carried or stored when not in use.
Still another object of the invention is to provide a pallet jack stop that is made of an environmentally safe dense rubber or similar material that has the strength, durability, elasticity and safety of composition to allow it to be subject to heavy cyclic loading, including impact loading under a wide range of environmental conditions.
It is an object of the invention to provide improved elements and arrangements thereof for the purposes described which is inexpensive, dependable and fully effective in accomplishing its intended purposes.